Charge receptacles for use in ion source units



ARC

Feb. 28, 1956 2,736,810

A. F. CLARK CHARGE RECEPTACLES FOR USE IN ION SOURCE UNITS Filed Nov. '7, 1945 2 Sheets-Sheet l HEATER SUPPLY FILAMENT Fig.1

su PPLY ACCELE RATING ELECTRODE SUPPLY J INVENTOR. ARNOLD F. CLARK BY @M azWm W ATTORNEY.

Feb. 28, 1956 CLARK 2,736,810

CHARGE RECEPTACLES FOR USE. IN ION SOURCE UNITS Filed Nov. 7, 1945 2 Sheets-Sheet 2 I213! 25 v -I 6/ E I" 2 0 50 5/ 0 E III- Illll I". r

| E E m I 23 I I I Q I 23 63 "I 24 g 0 2 g g I: so I 1 57 54 55 INVEN TOR.

5 I BY ARNOLD CLARK ATTORNEY.

United States Qatent CHARGE RECEPTACLES FOR USE IN ION SOURCE UNITS Arnold F. Clark, Berkeley, Calif., assignor to the United States of America as represented by the United States Atomic Energy Commission Application November 7, 1945, Serial No. 627,267

4 Claims. (Cl. 256-413) The present invention relates to calutron ion source units, and more particularly to apparatus for opening normally closed charge receptacles arranged therein.

At the outset, it is noted that a calutron is a machine of the character of that disclosed in the copending application of Ernest 0. Lawrence, Serial No. 557,784, filed October 9, 1944, and now Patent No. 2,709,222, granted May 24, 1955, and is employed to separate the constituent isotopes of an element.

Such a calutron ordinarily comprises an evacuated tank housing a removable ion source unit, formed principally of steel and including structure providing a charge reservoir and a communicating charge ionizing chamber.

Accordingly, it is an object of the present invention to provide in combination with a calutron comprising a closed tank housing an ion source unit including structure providing a charge ionizing chamber, an improved atrangement controllable from the exterior of the tank for opening a sealed charge receptacle into communication with the charge ionizing chamber of the ion source unit.

Another object of the invention is to provide a calutron ion source unit of improved construction and arrangement.

The invention will best be understood by reference to the following specification, taken in connection with the accompanying drawings in which Figure 1 is a diagrammatic plan view of .a calutron including an ion source unit embodying the present invention; Fig. 2 is a diagrammatic sectional view of the calutron taken along the line 2-.2 in Fig. 1; Fig. 3 is a longitudinal sectional view of the .calutron ion source unit; Fig. 4 is a front elevational view of the source unit shown in Fig. 3; Fig. 5 is a sectional view of the ion source unit and the associated end wall of the tank of the calutron, taken principally along the line 55 in Fig. 3, illustrating the mechanism for opening the charge receptacle contained in the charge reservoir of the source unit housed in the tank :of the 'calutron; and Fig. 6 is an enlarged fragmentary view, partly in section, of the charge receptacle opening mechanism shown in Fig. 5.

Referring now more particularly to Figs. 1 and 2 of the drawings, there is illustrated a representative example of a calutron 10 of the character noted, that comprises magnetic field structure including upper and lower pole pieces 11 and 12, provided with substantially flat parallel spaced-apart pole faces, and a tank 13 disposed between the pole faces of the pole pieces 11 and .12. The pole pieces 11 and 12 carry windings, not shown, which are adapted to be energized in order to produce a substantially homogeneous and relatively strong magnetic field therebetween, which magnetic field passes through the tank 13 and the various parts housed therein. The tank 13, preferably formed of steel, is of tubular configuration, being substantially crescent-shaped .in plan, and comprising substantially flat parallel spaced-apart top and bottom walls 14 and 15, upstanding curved inner and outer side walls 16 and 17, and end walls .18 and .19. The end walls '18 and '19 close the opposite ends of the 2,736,816 Patented Feb. 28, 1956 tubular tank 13 and are adapted to be removably secured in place, whereby the tank 13 is hermetically sealed. Also, vacuum pumping apparatus 13a is associated with the tank 13, whereby the interior of the tank 13 may be evacuated to a pressure of the order of 10- to 10* mm. Hg.

The removable end wall 18 suitably supports a source unit 20 comprising a charge receptacle 21 and a communicating arc-block 22. Receptacle 21 is provided with a removable cover 50 and along one side carriesa standard 64 adapted to support cathode structure 65. This cathode structure in turn comprises two terminals 66 over which is disposed shield 70 serving to prevent migration of such electrons upwardly in the longitudinal direction as may be emitted by the filamentary electrode 25 later to he described. An electric heater 23 is arranged in heat exchange relation with the charge receptacle 21 and is adapted to be connected to a suitablesource of heater supply, whereby the charge receptacle 21 may be appropriately heated, the'charge receptacle 21 being formed of steel or the like. Communicating with receptacle 21, asby means of a tubular member 56, is an arc block 22 having an upstanding arc chamber 55 defined by a frame member 58 supporting a baffle plate 59 preferably formed of carbon or graphite. The are block may be suitably heated by a heater 57 and the frame member 58 may be secured to the wall structure of the arc block as by means of two upstanding strips 60. Frame member 58 moreover includes a top wall portion 61, two upstanding substantially parallel spaced-apart side walls 62 and a front wall 63 having the slot 24 formed therein and communicating with are chamber 55. Top wall portion 61 is formed with a transversely extending slot 67 having a counterrecess 68 adapted to receive electrode 27 later to be described. This electrode in turn is provided with a transversely extending slot 28 communicating with slot 67 and therethrough with chamber 55. The arc-block '22 is formed, at least partially, of carbon or graphite and is substantially C-shaped in plan, an upstanding slot 24 being formed in the wall thereof remote from the charge receptacle 21. Thus, the arc-block 22 is of hollow construction, the cavity therein communicating with the interior of the charge receptacle 21.

Also, the removable end wall 18 carries a filamentary cathode 25 adapted to be connected to a suitable source of filament supply, the filamentary cathode 25 overhanging the upper end of the arc-block 22 and arranged in alignment with respect to the upper end of the cavity formed "therein. The arc-block 22 carries an anode 26 disposed adjacent the lower end thereof and arranged in alignment with respect to the cavity formed therein and mounted in slot 69 formed in wall 63. Also, the arc-block 22 carries a collimating electrode '27 disposed adjacent the upper end thereof and having an elongated collimating slot 28 formed therethrough and arranged in alignment with respect to the filamentary cathode 25 as well as the anode 26 and the cavity formed in the arc-block 22. Both the anode 26 and the collimating electrode 27 are electrically connected to the source unit 20, which .in turn is grounded; likewise, the tank 13 is grounded. Also, the filamentary cathode 25 and the cooperating anode 26 are adapted to be connected to a suitable source of arc supply.

Further, the removable end wall 18 carries ion accelerating structure 29 formed of carbon or graphite and disposed in spaced-apart relation with respect to the wall of the arc-block 22 in which the slot 24 is formed. More specifically, a slit Si) is formed in the ion accelerating structure 29 and arranged in substantial alignment with respect to the slot 24 formed in the wall of .the arcblock 22. A suitable source .of accelerating electrode supply is adapted to be connected between the arc-block 22 and the ion accelerating structure 29, the positive and negative terminals of the supply mentioned being respectively connected to the arc-block 22 and to the ion accelerating structure 29. Further, the positive terminal of the accelerating electrode supply is grounded.

The removable end wall 19 suitably supports a collector block 31 formed of stainless steel or the like and provided with two laterally spaced-apart cavities or pockets 32 and 33 which respectively communicate with aligned slots 34 and 35 formed in the wall of the collector block 31 disposed remote from the removable end wall 19. It is noted that the pockets 32 and 33 are adapted to receive two constituent isotopes of an element which have been separated in the calutron 10, as explained more fully hereinafter. Further, the inner wall 16 suitably supports a tubular liner 36 formed of copper or the like, rectangular in vertical cross-section, disposed within the tank 13 and spaced from the walls 14, 15, 16 and 17. One end of the tubular liner 36 terminates adjacent the accelerating structure 29; and the other end of the tubular liner 36 terminates adjacent the collector block 31; the tubular liner 36 constituting an electrostatic shield for the high velocity ions traversing the curved paths between the slit 30 formed in the ion accelerating structure 29 and the slots 34 and 35 formed in the collector block 31, as explained more fully hereinafter. Finally, the tubular liner 36 is electrically connected to the ion accelerating structure 29 and to the collector block 31, each of these elements being electrically insulated from tank 13 by any suitable means (not shown).

Considering now the general principle of operation of the calutron 10, a charge comprising a compound of the element to be treated is placed in the charge receptacle 21, the compound of the element mentioned being one which may be readily vaporized. The end walls 18 and 19 are securely attached to the open ends of the tank 13, whereby the tank 13 is hermetically sealed. The various electrical connections are completed and operation of the vacuum pumping apparatus 13a associated with the tank 13 is initiated. When a pressure of the order of 10- to mm. Hg is established within the tank 13, the electric circuits for the windings, not shown, associated with the pole pieces 11 and 12 are closed and adjusted, whereby a predetermined magnetic field is established therebetween traversing the tank 13. The electric circuit for the heater 23 is closed, whereby the charge in the charge receptacle 21 is heated and vaporized. The vapor fills the charge receptacle 21 and is conducted into the communicating cavity formed in the arc-block 22. The electric circuit for the filamentary cathode 25 is closed, whereby the filamentary cathode is heated and rendered electron emissive. Then the electric circuit between the filamentary cathode 25 and the anode 26 is closed, whereby an arc discharge is struck therebetween, electrons proceeding from the filamentary cathode 25 through the collimating slot 28 formed in the collimating electrode 27 to the anode 26. The collimating slot 28 formed in the collimating electrode 27 defines the cross-section of the stream of electrons proceeding into the arc-block 22, whereby the arc discharge has a ribbon-like configuration and breaks up the molecular form of the compound of the vapor to a considerable extent, producing positive ions of the element that is to be enriched with the selected one of its isotopes.

The electric circuit between the arc-block 22 and the ion accelerating structure 29 is completed, the ion accelerating structure 29 being at a high negative potential with respect to the arc-block 22, whereby the positive ions in the arc-block 22 are attracted by the ion accelcrating structure 29 and accelerated through the voltage impressed therebetween. More particularly, the positive ions proceed from the cavity formed in the arc-block 22 l through the slot 24 formed in the wall thereof, and across the space between the ion accelerating structure 29 and the adjacent wall of the arc-block 22, and thence through the slit 30 formed in the ion accelerating structure 29 into the interior of the tubular liner 36. The high-velocity positive ions form a vertical upstanding ribbon or beam proceeding from the cavity formed in the arc-block 22 through the slot 24 and the aligned slit 30 into the tubular liner 36.

As previously noted, the collector block 31, as well as the tubular liner 36, is electrically connected to the ion accelerating structure 29, whereby there is an electricfield-free path for the high-velocity positive ions disposed between the ion accelerating structure 29 and the collector block 31 within the tubular liner 36. The highvelocity positive ions entering the adjacent end of the liner 36 are deflected from their normal straight-line path and from a vertical plane passing through the slot 24 and the aligned slit 3%, due to the effect of the relatively strong magnetic field maintained through the space within the tank 13 and the liner 36 through which the positive ions travel, whereby the positive ions describe arcs, the radii of which are proportional to the square roots of the masses of the ions and consequently of the isotopes of the element mentioned. Thus, ions of the relatively light isotope of the element describe an interior arc of relatively short radius and are focused through the slot 34 into the pocket 32 formed in the collector block 31; whereas ions of the relatively heavy isotope of the element describe an exterior arc of relatively long radius and are focused through the slot 35 into the pocket 33 formed in the collector block 31. Accordingly, the ions of the relatively light isotope of the element are collected in the pocket 32 and are de-ionized to produce a deposit of the relatively light isotope of the element therein; while the ions of the relatively heavy isotope of the element are collected in the pocket 33 and are de-ionized to produce a deposit of the relatively heavy isotope of the element therein.

After all of the charge in the charge receptacle 21 has been vaporized, all of the electric circuits are interrupted and the end wall 18 is removed so that another charge may be placed in the charge receptacle 21 and subsequently vaporized in the manner explained above. After a suitable number of charges have been vaporized in order to obtain appropriate deposits of the isotope of the element in the pockets 32 and 33 of the collector block 31, the end wall 19 may be removed and the deposits of the collected isotopes in the pockets 32 and 33 in the collector block 31 may be reclaimed.

Referring now to Figs. 3, 5, and 6 of the drawings, the charge bottle 52 illustrated constitutes a receptacle, and is formed of glass or other frangible material, as previously noted. More specifically, the charge bottle 52 includes a flat bottom wall 80, an upstanding cylindrical side wall 81, and a substantially semispheroidal top wall 82 terminating in an upwardly projecting hollow nipple I 83. Preferably in the charge bottle 52, the wall structure of the nipple 83 is relatively thin with respect to the wall structure of the top wall 32, whereby the nipple 83 constitutes a frangible portion that may be readily broken off in order to provide an opening through the top wall 82 communicating between the interior of the charge bottle 52 and the cavity 51 formed in the charge receptacle 21.

Further, the source unit 20 comprises an arrangement controllable from the exterior of the tank 13 of the calutron 10 for opening the charge bottle 52; this arrangement comprising a clip 84 removably attached to the nipple 83 provided on the charge bottle 52, and a connected flexible pull wire 85. More particularly, the clip 84 comprises a substantially C-shaped body that is adapted to engage the nipple 83 and to be retained in place by a latch 86, one end of the latch 86 being pivotally secured to one end of the C-shaped body and the other end of the latch being adapted to be sprung over the other end of the C-shaped body, as clearly illustrated in Fig. 6. The pull wire-85 extends through an opening 87 formed in the cylindrical side wall of the charge receptacle 21 and into a surrounding fixture 88, carried by the cylindrical side wall mentioned, and terminates in a control rod 89 extending through an opening 90 formed in the end wall 18 of the tank 13 of the calutron 10.

More specifically, the control rod 89 extends from the exterior through the opening 90 formed in the end wall 18 into the interior of the tank 13, and is mounted for longitudinal sliding movement in sealed relation with respect to the end wall 18 by an arrangement including a seal 91 and a bushing 92, the extreme outer end of the control rod 89 carrying a handle 89a to facilitate manipulation thereof. More particularly, the seal 91 is of conventional construction and arrangement and includes an annular flange 93 secured to the exterior surface of the end wall 18 in surrounding relation with respect to the opening 90 formed therein; whilethe bushing 92 includes an annular flange 94 secured to the interior surface of the end wall 18 in surrounding relation with respect to the opening 90 formed therein. Further, the annular flanges 93 and 94, respectively arranged exteriorly and interiorly of the end wall 18, slidably support the control rod 89.

The bushing 92 further includes an inwardly extending tubular projection 95 surrounding the control rod 89, the inner end of the control rod 89 being secured to the outer end of the pull wire 85, as previously noted, within the tubular projection 95. Specifically, the outer end of the pull wire 85 extends into a centrally disposed opening 96 drilled in the inner end of the control rod 89, and is secured in place by an arrangement including a set screw 97 disposed in a threaded opening formed in the inner end of the control rod 89. Further, the longitudinal sliding movement of the control rod 89 through the opening 90 formed in the end wall 18 is limited and guided by an arrangement including a snap-on ring 98, removably secured in an annular groove formed in the control rod 89 adjacent the extreme inner end thereof, the exterior surface of the snap-on ring 98 engaging the interior surface of the tubular projection 95. Finally, the extreme inner end of the tubular projection 95 carries a fixture 99 which supports one end of a flexible tubular casing or shield 100 surrounding the pull wire 85, the other end of the casing 100 being secured to the fixture 88 carried by the cylindrical wall of the charge receptacle 21.

Accordingly, the control rod 89 is mounted for limited longitudinal sliding movement through the opening 99 formed in the end wall 18, and in sealed relation with respect to the end wall 18 by virtue of the arrangement including the seal 91, whereby the control rod 89 may be moved longitudinally with respect to the end wall 18 from the exterior of the casing 13 of the calutron 10. The inner end of the control rod 89 is rigidly secured to the outer end of the pull wire 85, whereby the pull wire 85 may be moved back and forth within the surrounding flexible casing 100 and irrespective of the alignment of the control rod 89 and the nipple 83 carried by the top wall 82 of the charge bottle 52. Thus, when the control rod 89 is moved outwardly with respect to the end wall 18, the pull wire 85 is moved outwardly, whereby the clip 84 engaging the nipple 83 exerts a force thereon, causing this frangible nipple 83 to be broken off of the top wall 82 of the charge bottle 52, in order to place the charge 53 contained 'in the charge bottle 52 into communication with the cavity 51, whereupon the previously described separatory action upon the gaseous materials issuing from the ruptured charge bottle or receptacle can take place within the calutron.

Considering now the construction and arrangement of the charge bottle 52 with reference to its operation in the source unit 20, it is noted that in the example illustrated, the charge bottle 52 is filled with a charge 53, evacuated, and hermetically sealed, all prior to use.

The previously prepared charge bottle 52 containing the charge 53 is then placed in the cylindrical cavity 51 formed in the charge receptacle 21, the clip 84 carried on the inner end of the pull wire is attached to the nipple 83 provided on the top wall 82 of the charge bottle 52, the clip 84 is secured in place by the latch 86, and the cover 50 for the charge receptacle 21 is secured in place. The end wall 18 carrying the source unit 20 is then moved into relation with respect to the associated end of the tank 13 and secured in place. Operation of the pumping apparatus 13a is initiated, and shortly thereafter, when the pressure in the tank 13 is lowered to the order of 10- to l0 mm. Hg the electric circuits for the windings, not shown, associated with the pole pieces 11 and 12. are closed and adjusted in order to establish the predetermined magnetic field therebetween, traversing the tank 13, as previously noted.

At this time, the control rod 89 is moved outwardly with respect to the end wall 18 by manipulation of the handle 89a, whereby the pull wire 85 is moved outwardly within the casing 100, causing the clip 84 to exert a force upon the nipple 83 in order to break the nipple 83 off of the top wall 82 of the charge bottle 52' At this time, the interior of the charge bottle 52 communicates with the cavity 51 and the circuit for the heater 23 is closed, whereby the charge receptacle 21 and consequently the charge bottle 52 is heated, effecting heating of the contained charge 53. When the charge 53 contained in the charge bottle 52 is thus heated, it is vaporized and conducted through the opening formed in the top wall 82 into the cavity 51, whereby the cavity 51 is filled with the vapor, and the vapor is conducted through the tubular member 56 into the distributing chamber 54, as previously explained.

In view of the foregoing, it is apparent that a source unit for a calutron has been provided that comprises a charge receptacle receiving a removable hermetically sealed charge bottle, and an improved arrangement for opening the charge bottle after it has been placed in the charge receptacle in the source unit within the tank of the calutron and operation of the calutron has been initiated.

While there has been described what is at present considered to be the preferred embodiment of the invention, it will be understood that various modifications may be made therein. The invention therefore is intended to be restricted only insofar as set forth in the following claims.

What is claimed is:

1. In combination with a calutron comprising a closed tank housing an ion source unit including structure wholly disposed within the magnetic field of said calutron and providing a charge reservoir and a communicating charge ionizing chamber, means adapted to evacuate said tank to a pressure substantially below atmospheric, a normally sealed receptacle having a frangible portion and containing a char e and positioned within said charge reservoir, a pull element connected to said frangible portion and extending to the exterior of said closed tank, and means sealing said pull element in movable relation to said tank wall, whereby the element may be pulled and the receptacle broken, permitting the charge to fill said reservoir and enter said communicating charge ionizing chamber.

2. A calutron comprising a closed tank, an ion source unit housed therein including structure wholly disposed within the magnetic field of said calutron and providing a charge reservoir and a communicating charge ionizing chamber, means adapted to evacuate said tank to a pressure substantially below atmospheric, a normally sealed receptacle having a frangible nipple and containing a charge and positioned within said charge reservoir, pull means controllable from the exterior of said closed tank and connected to said frangible nipple for breaking the nipple ofi of said said receptacle, and means sealing said pull means inmovable relation to said tank wall, whereby the charge in said receptacle fills said charge reservoir and enters said communicating charge ionizing chamber.

3. In combination, a calutron having a closed tank, means adapted to evacuate said tank to a pressure substantially below atmospheric, an ion source housing having a major axis and disposed in said tank in communication therewith, a sealed charge receptacle mounted in said housing along the major axis thereof and substantially immovable transversely of said major axis, said receptacle having a frangible portion, a pull element connected to said frangible portion and extending substantially transversely of the major axis of the housing, and a seal in the wall of said tank through which said pull element extends, said seal being adapted to maintain the pressure conditions within the tank during actuation of the pull element, whereby upon actuation of the pull element from a position remote from the receptacle and externally of the tank the frangible portion of the receptacle may be broken thereby to permit escape of the charge therein into said tank.

4. An apparatus as described in claim 3 wherein said frangible portion of the receptacle is located adjacent the upper extremity of said receptacle.

References Cited in the file of this patent UNITED STATES PATENTS 1,231,416 Needham June 26, 1917 2,221,467 Bleakney Nov. 12, 1940 2,374,205 Hoskins Apr. 24, 1945 FOREIGN PATENTS 350,069 Great Britain June 11, 1931 

1. IN COMBINATION WITH A CALUTRON COMPRISING A CLOSED TANK HOUSING AN ION SOURCE UNIT INCLUDING STRUCTURE WHOLLY DISPOSED WITHIN THE MAGNETIC FIELD OF SAID CALUTRON AND PROVIDING A CHARGE RESERVIOR AND A COMMUNICATING CHARGE IONIZING CHAMBER, MEANS ADAPTED TO EVACUATE SAID TANK TO A PRESSURE SUBSTANTIALLY BELOW ATMOSPHERIC, A NORMALLY SCALED RECEPTACLE HAVE A FRANGIBLE PORTION AND CONTAINING A CHARGE AND POSITIONED WITHIN SAID CHARGE RESERVIOR, A PULL ELEMENT CONNECTED TO SAID FRANGIBLE PORTION AND EXTENDING TO THE EXTERIOR OF SAID CLOSED TANK, AND MEANS SEALING SAID PULL ELEMENT IN MOVABLE RELATION TO SAID TANK WALL, WHEREBY THE ELEMENT MAY BE PULLED AND THE RECEPTACLE BROKEN, PERMITTING THE CHARGE TO FILL SAID RESERVIOR AND ENTER SAID COMMUNICATING CHARGE IONIZING CHAMBER. 